In order to acquire a 3D image of the left atrium using a rotational angiography system, it is necessary to position the left atrium at iso-center of the angiography system. The placement of a left atrium at iso-center for imaging ensures that the region of interest (i.e. left atrium) does not drift out of a displayed field of view. Known systems involve use of a catheter placed in a left pulmonary artery that is positioned anterior to a left atrium. In the known systems iso-centering of a Left Atrium of a heart in the frontal position is performed by an operator under fluoroscopy (live reduced dose X-ray imaging) moving a patient support table horizontally until the spinal vertebrae are about 1.5 cm on the left of the image center line and by moving the table longitudinally until the catheter that was positioned in the left pulmonary artery is placed at the top of the image. Iso-centering in the lateral position is performed by an operator moving the support table up or down until two thirds of the vertebrae body is visible on the right of the image. This is a slow and inaccurate procedure involving substantial risk in placing of a catheter. A system according to invention principles addresses this deficiency and related problems.